At the core of parachute regiment training are simple drill exercises you can do anywhere in the world, with no trainer or equipment. The following three exercises cover all the major muscle groups: try three sets of each every other day (I advise doing cardio exercises on the days in between); do as many reps as you can until you’re struggling. You’ll quickly notice how many more you can manage.

Squat Stand with your feet apart, arms out in front, lower your bottom, keeping your thighs parallel to the floor.

Plank From lying flat on your stomach, raise on to your forearms and tiptoes, tilt your pelvis forward, keep your back straight, and hold for as long as you can. If you need a harder workout, try using three points of contact by raising one leg.

Push-up Start from an arm plank(hands on the floor, arms straight, back straight) lower to the floor bending your elbows out, and repeat.

• Major Sam McGrath is author of Be Para Fit: The 4-Week Formula For Elite Physical Fitness (£14.99, Osprey).